The safety of immune globulin products, in regard to hepatitis C (HC), manufactured from anti-HCV depleted plasma pools, is being studied in chimpanzees and is still in progress. As reported last year, plasma from anti-HCV negative Source Plasma donations was pooled and fractionated into intravenous immune globulin (IVIG). Samples from the unprocessed plasma pool were inoculated into 2 chimpanzees. These animals became infected with HCV as demonstrated by the development of anti-HCV, ALT elevations and the detection of HCV-RNA in the plasma. IVIG was then inoculated into 3 chimpanzees. If any of these animals had developd HC, it would have implied that screening for anti-HCV is deleterious to the safety of IVIG. If none of these animals had developed HC, it would suggest that screening plasma for anti-HCV will not adversely affect immune globulin safety. Twelve months after inoculation of IVIG had passed, none of the animals showed any evidence of hepatitis infection. This data was used as the basis to recommend the screening of source plasma for anti-HCV. Subsequently two animals were challenged with known infectious human plasma to ensure the capability of infectivity, and a third animal remained unchallenged and serves as a control. One of the animals that was challenged with HCV has seroconverted.